Electrode holder for electric furnaces



J. SOUCHET ELECTRODE HOLDER FOR ELECTRIC FURNACES Filed Feb. 16, 1961 INVEN TOR. JOSEPH SOUCHET' BY /2/W?" A TTORNEY Feb. 25, 1964 w 1 I L mu7//// R r 3,122,600 ELECTRODE HOLDER FOR ELECTRIC FURNACES JosephSouchet, Riouperoux, France, assignor to Solumeta, Paris, France, acorporation of France Filed Feb. 16, 1961, Ser. No. 89,747 Claimspriority, application France Feb. 17, 1960 5 Claims. (Cl. 13-14) Thepresent invention, which is based on the researches of the applicant,relates to electrode holders for electric furnaces. It is particularlyapplicable to electric holders which are to be provided for sealed(closed) furnaces.

It is well known to improve the contact between an electrode and itscurrent inlet clamp by increasing the contact surfaces. Thus, it isfound advantageous, especially in the case of large diameter electrodes,to use clamps comprising a plurality of contact plates which, generally,are pivotally connected among themselves and pressed (clamped) onto theelectrode.-

It is, nevertheless, difficult to increase to any large extent thenumber of contact plates, because the relative size of the spacesbetween the plates, with regard to the width of the latter, increasesand, hence, there is no longer any gain in contact surface. For thisreason, one is generally limited to six or eight contact plates, theelectrode being then clamped on about 70% of its periphery.

The present invention makes it possible to increase in a large ratio thecontact surface between the current inlet and the electrode because thetotality of the electrode periphery is utilized for the current inlet.At the same time, the invention makes it possible to obtain a tight sealbetween the electrode and the electrode holder.

The present invention comprises the obtainment of electric contactbetween the electrode and the one or more elements of the electrodeholder which receive the current, by packing between these two parts acomminuted or powdered material, which conducts the electric cur rentand which is heat resistant.

In a preferred but non-lirniting embodiment of the invention, theelectrode holder is provided with a metallic tubular part or sleeve,which is concentric with the electrode and having an internal diameterlarger than the diameter of the electrode, and acomminuted material isdisposed in the annular. space between these two parts, means beingprovided for maintaining this material in a compacted condition.

According to the invention, the contact is established uniformly overthe entire periphery of the electrode, thereby avoiding formation of hotspots or burned areas.

According to the intensity of the operating current of the electrode,the sleeve is chosen of a more or less greater length, and the currentdensity is maintained between the usual limits by increasing the contactsurface between the conducting powdered material and the electrode.

As conducting divided material, there is advantageous- United StatesPatent 0 3,122,600 Patented Feb. 25, 1964 one embodiment which has givengood results, the upper part of the sleeve comprises a screw-typestufling box which compresses the graphite in the annular space providedtherefor.

A still better contact is secured when the internal surface of thesleeve is given a slightly truncated profile (shape), the small basebeing directed towards the tip of the electrode; There is then produceda wedging effect which facilitates packing ofthe graphite.

The novel device according to the invention presents the advantage ofproviding not only an excellent electric joint, but also a joint whichis sealed to gases between the electrode and the'part where the currentis introduced, the said joint nevertheless enabling relativedisplacement between the electrode and the partwhere the current isintroduced.

As a result of this fact, the novel electrode is especially advantageouswhen used for electric furnaces where the atmosphere of the hearth mustbe different in pressure and/or composition from the externalatmosphere.

In a preferred but non-limiting embodiment of the invention, there areprovided secondary tightening means for the electrode, the saidsecondary tightening means merely having a mechanical blocking functionand being integral with the current inlet sleeve.

Moreover, there are provided, as usual, longitudinal translation meansfor the electrode for control purposes, the said means acting preferablyon the sleeve or on the above-mentioned secondary tightening means forthe elec trode.

According to the invention, there is obtained a sealed (tight) electrodeholder by additionally providing between the parts of the electrodeholder which are subjected to relative longitudinal displacement, tightsliding (expansion) joints of a heat-resistant material.

The present invention finds a particularly important application in thecase where it is desired to obtain a sealed (tight) electrode holder, ofvariable inclination, an arrangement which makes it possible to maintainoptimum spacing between the electrodes of the same furnace, in spite ofvariations in the level of the bath ly used graphite in the form ofpowder and/or flakes.

Good results are obtained by using a mixture of these two products, abetter conductivity having been obtained by employing a mixture ofapproximately equal parts of powder and flakes.

One can also use for the conducting joint, in Whole or in part, carbidesof refractory metals such as, and without limitation, carbides oftungsten, of molybdenum, of tantalum, of titanium, of zirconium, etc.

In a preferred embodiment of the invention, the sleeve is provided atits lower end with one or more packing rings to avoid loss of graphite,aloss which can be produced by entrainment when the electrode isdisplaced relatively to the sleeve.

Means are provided for pressing the graphite-at least when theelectrodes are under current-both against the electrode and against thecurrent inlet sleeve. Thus, in

therein.

The fixed part in the space of the electrode holder comprises a fixedsector-shaped base (seat), for example, on the roof of the furnace, andon whichis mounted an element, or electrode guide, having a surfacecomplementary to that of the sector-shaped base.

By way of non-limiting examples, there are described below variouspreferred embodiments of the invention with reference to the annexeddrawing in which FIGURE 1 represents, in (half) section, a current inletarrangement according to the invention, and

FIGURE 2 shows in (half) section an embodiment of a sealed electrodeholder having a variable inclination.

Aswill be seen by reference to FIGURE 1, the sleeve 1 of the electricholder has a slightly truncated internal surface 2. The electric currentis led into said sleeve, for example, by means of a lug (thimble,socket) 3 connected to the cable 4. The sleeve 1 is moreover supportedby any convenient means on a stationary portion of the installation,such as a cross piece, furnace roof, etc., not illustrated in thedrawing, by the intermediary of any suitable longitudinal translationmeans such as a jack, pulley block, etc., which makes it possible toregulate the elevation of the electrode.

The electrode 5, is clamped in a locking collar (clamp) 6 integral withthe sleeve 1, or integral with a part which is itself integral with saidsleeve. i

The space 7 between the electrode and the internal face 2 of the sleeveis provided with a mixture of graphite scales and powder which isretained at the bottom by a) one or more graphite rings 8, and which iscompressed by means of a stufiing-box 9.

When the electrode holder is intended for a large diameter electrode,supplementary guiding rings are advantageously provided for theelectrode, in order that the electrode not be forced on the graphitering 8.

The said ring 3 has for its object to retain the powderscale graphitemixture 'while permitting sliding of the electrode, so that its diametershould be adjusted with precision. In the case where the electrodediameter tolerances are appreciable, it may be advantageous to superposeseveral slit graphite rings, taking care that the slots are opposite toeach other.

During operation of the furnace, a certain quantity of the graphitepowder may be entrained, particularly so during the sliding operationsof the electrode or during passage of the connecting nipples; it is forthis reason that there is provided a guard on the stuffingbox 9 whichcan be periodically tightened when this becomes necessary.

Without departing from the scope of the invention, provision can be madein the case of electrodes of small diameters to carry out the mechanicaltightening of the electrode in the electrode holder solely by means ofthe conductive joint of graphite scales, thereby eliminating thetightening clamp. It is advantageous to provide the stufiing-box with aremote control system, for example, one using a jack, whereby it ispossible to release rapidly the clamping pressure of the flake joint, tofacilitate sliding of the electrode.

On FIGURE 2 there is illustrated a special embodiment of the presentinvention in which advantage is taken of the seal (tightness) securedbetween the current inlet sleeve 1 and the electrode by reason of theprovision of a conductive joint of graphite flakes.

FIGURE 2 shows a sealed (tight) and orientable electrode holder, whichmakes it possible to obtain a very precise regulation of arc furnacesprovided with a controlled atmosphere.

In this embodiment, the electric contact between the sleeve 1, cooled bycirculation of water in the tubes and the electrode 5 is assured, aspreviously described, by means of graphite powder and flakes which arepacked in the space 7 by means of the stufiing-box 9, while themechanical clamping of the electrode on the electrode holder iscompleted by a locking ring 6 integral with the sleeve.

The sleeve 1 is extended by a tubular skirt 11, likewise cooled, andcomprising at its lower part a sealing joint 12 secured into astuffing-box. The said joint is susceptible of sliding with atranslation motion on the external surface of a tubular electrode guide13, cooled by water circulation and eventually comprising a ring 14, ora portion of a ring, for guiding or supporting the electrode when thelatter is not vertical, said guide being not liable to any translationmotion.

Regulation of the electrode in height is carried out by means of anyusual regulating device such as-illustrated by way of example on FIGURE2one or more jacks 15 the cylinders of which rest on a fixed part usedin the translation of the electrode holder, such as the tubular guide13, and the pistons 16 of which act on the sleeve 1 or on a part whichis integral with the latter.

To enable sliding motion, as the electrode is consumed, there isadvantageously provided on the upper part of the electrode holder aguiding ring 17 integral with the fixed part of the electrode holder(part 13) through the intermediary of cheek plates, not shown on FIGURE2.

When the pistons 16 of the jack 15 are at the end of their stroke and intheir lower position, a collar 19 is pressed on the electrode which thenrests on the fixed ring 17. The collar 6 is loosened and the electroderetained by the collar 19 remains stationary while the jacks areoperated to raise the current inlet assembly.

The ring 6 is then re-cl-amped and the collar 19 is loosened, to againpermit operation of the electrode by means of the jacks 15.

According to the preferred, although non-limiting, embodiment shown onFIGURE 2, the inclination of the electrode holder is rendered variableby providing for the tubular electrode guide 16, a cylindrical lowersup-. porting surface 2t) which rests on a corresponding surface of acooled base 22-22 comprising an insulating joint 23 and fixed, forexample, to the roof 24 of the furnace.

As will be readily understood, suitable means for pressing thecylindrical surfaces 2% and 22 against each other prevent any accidentalinclination of the electrode holder, and flexible joints, such as 25,insure complete tightness of the pivoting arrangement.

As will be understood, any other modifications comprising variantembodiments of those which have been described in detail above comewithin the scope of the invention.

1 claim:

1. In an electric furnace, in combination: an electrode, a tubularelectrode holder sleeve surrounding said electrode, spaced therefrom andprovided with tubes for circulating a cooling medium; a divided, heatresistant conductive, carbon containing material in the space betweenthe sleeve and the electrode, said space being defined by a conicalsurface; a current inlet arrangement for said holder and means forpassing current into the latter; means for compressing the dividedmaterial to thereby establish at the same time close electric con-tactand sealing to gases between the sleeve and the electrode; a jack deviceintegrally joined with both the sleeve and an electrode guide; anelectrode clamping device in-tegrally joined with the sleeve and adaptedto operate during the time of current passing into said holder and to betemporarily loosen-ed during the upward movement of said sleeve; anotherelectrode clamping device 19, independent cf said sleeve, integrallyjoined with the electrode guide and adapted to be loosened during thetime of current passing into said holder and to operate during said lastmentioned upward movement; said jack device regulating the electrode inheight.

2. An electric furnace according to claim 1, wherein the electrodeholder sleeve comprises a downwardly ex tending tubular skirt having asealing joint at its lower part secured into a stufiing box, therebyperfecting the gas-tightness of the electrode holder.

3. An electric furnace according to claim 1, provided with means forvarying the inclination of the electrode, said means comprisingcomplementary cooled sectorshaped parts, one of which is. integrallyjoined with the electrode guide, the other of which is integrally joinedwith the roof of the furnace.

4. An electric furnace according to claim 2, wherein the electrode guideis provided with a guiding ring.

5. An electric furnace according to claim 3, wherein the electrode guideis provided with a guiding ring.

References Cited in the file of this patent UNITED STATES PATENTS846,521 Stevens Mar. 12, 1907 871,338 Heroult Nov. 19, 1907 908,407Heroult Dec. 29, 8 1,173,960 Hechenbleikner Feb. 29, 1916 1,252,633 VomBaur Jan. 8, 1918 1,363,815 Saklatwalla et a1 Dec. 28, 1920 1,637,052Robinson July 26, 1927 1,737,890 Noichl et a1. Dec. 3, 1929 2,405,236Rhoades et al Aug. 6, 1946

1. IN AN ELECTRIC FURNACE, IN COMBINATION: AN ELECTRODE, A TUBULARELECTRODE HOLDER SLEEVE SURROUNDING SAID ELECTRODE, SPACED THEREFROM ANDPROVIDED WITH TUBES FOR CIRCULATING A COOLING MEDIUM; A DIVIDED, HEATRESISTANT CONDUCTIVE, CARBON CONTAINING MATERIAL IN THE SPACE BETWEENTHE SLEEVE AND THE ELECTRODE, SAID SPACE BEING DEFINED BY A CONICALSURFACE; A CURRENT INLET ARRANGEMENT FOR SAID HOLDER AND MEANS FORPASSING CURRENT INTO THE LATTER; MEANS FOR COMPRESSING THE DIVIDEDMATERIAL TO THEREBY ESTABLISH AT THE SAME TIME CLOSE ELECTRIC CONTACTAND SEALING TO GASES BETWEEN THE SLEEVE AND THE ELECTRODE; A JACK DEVICEINTEGRALLY JOINED WITH BOTH THE SLEEVE AND AN ELECTRODE GUIDE; ANELECTRODE CLAMPING DEVICE INTEGRALLY JOINED WITH THE SLEEVE AND ADAPTEDTO OPERATE DURING THE TIME OF CURRENT PASSING INTO SAID HOLDER AND TO BETEMPORARILY LOOSENED DURING THE UPWARD MOVEMENT OF SAID SLEEVE; ANOTHERELECTRODE CLAMPING DEVICE 19, INDEPENDENT OF SAID SLEEVE, INTEGRALLYJOINED WITH THE ELECTRODE GUIDE AND ADAPTED TO BE LOOSENED DURING THETIME OF CURRENT PASSING INTO SAID HOLDER AND TO OPERATE DURING SAID LASTMENTIONED UPWARD MOVEMENT; SAID JACK DEVICE REGULATING THE ELECTRODE INHEIGHT.